import java.util.Arrays;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner num = new Scanner(System.in);
        while(num.hasNextInt()) {
            int size = 7;
            int[] arr = new int[size];
            for (int i = 0; i < arr.length; i++) {
                arr[i] = num.nextInt();
            }
            Arrays.sort(arr);
            int sum = 0;
            for (int i = 1; i <= 5; i++) {
                sum += arr[i];
            }
            double ave = sum / 5.0;
            System.out.printf("%.2f\n", ave);
        }
    }
}